In building construction, the primary barrier between the interior environment and the unstable exterior environment is provided by multiple layers of a variety of materials.
Although combinations of materials have been developed capable of providing thermal insulation and a moisture barrier, these capabilities are undermined when there are holes or discontinuities in the barrier material. These holes and discontinuities result in excessive heat loss (or heat infiltration into air-conditioned structures) through air infiltration. The air that infiltrates the barrier carries moisture that is retained, causing mold growth and damage or impaired durability.
One of the primary tools to address these problems is the use of house wraps and other air barriers and vapor retarders.
Although house wraps have decreased the amount of moisture entering the interior of buildings, the associated air tightness of the barriers has resulted in a reduction in the drying ability of the barrier materials.
Further the performance of the barrier materials continues to depend on the quality of workmanship for installing the materials. If there are gaps or discontinuities between adjacent sections of house wrap, then infiltration can occur.
Recently, gypsum sheathing has been used outdoors in exterior insulation or finishing systems, with insulation layers, (sometimes referred to as “Exterior Insulation and Finish Systems (EIFS)”). These systems are designed to accept polystyrene insulation adhered to a glass-faced gypsum board, followed by a thin application of stucco, for example. Because of the exposure to the elements, gypsum sheathing boards are often treated or impregnated with hydrophobic additives.
U.S. Pat. No. 5,644,880, incorporated by reference herein, describes an EIFS, for which the essential components comprise a fibrous mat-faced, water-resistant gypsum board and an overlying finishing material. The finishing material can be in multi-ply or mono-ply form. It can be positioned contiguously to said gypsum board or it can directly overlie or be directly affixed to a member(s) which is sandwiched between said gypsum board and said finishing material.
Improved building products are desired.